1. Field of the Invention
This invention relates to an integrated dust sensing assembly for a vehicle air intake system. Specifically, a dust sensor is mounted to an intake manifold or integrated into a mass air flow sensor unit to monitor the dust intake to an engine.
2. Related Art
Internal combustion engines include air induction systems for conducting air to the engine. Engine noise is propagated through the air induction systems, which is undesirable. Noise attenuation mechanisms have been installed within the air induction systems to reduce these noises. Typically these noise attenuation mechanisms include a speaker, a sound detector, a signal generator, and various other components that are used to reduce noise generated by the air induction system. These components are mounted within an air duct housing.
Often, the air that is drawn into the system through the air duct housing includes dust, dirt, and other particulate contaminants. These contaminants can clog the engine resulting in poor performance. An air filter is typically installed within the air induction system to remove these contaminants from the airflow prior to the air being drawn into the engine. Sometimes the air filter is not properly installed or becomes damaged during vehicle operation, which allows the contaminants to enter the engine. It is desirable to be able to accurately monitor dust, dirt, and particulate concentration levels before the air enters the engine to determine if the air filter system is operating properly.
One disadvantage with air filters is that the system experiences a pressure drop as the air is drawn through the filter. Even when the airflow is generally clean, i.e., the air does not include a high level of contaminants, the air is drawn through the filter. It is desirable to include a by-pass mechanism that works in conjunction with a particulate monitor to by-pass the filter mechanism when the airflow has minimal particulate concentrations.
It is the object of the present invention to provide a simple and effective apparatus and method for monitoring particulate concentrations to overcome the deficiencies outlined above.
An air intake or induction system includes a particulate sensor that sends a particulate signal representative of the particulate concentration entering a vehicle engine to an output device monitored by a vehicle operator. If particulate concentration levels are higher, the signal can alert the operator that the filter is improperly installed, the filter has a hole or other damage, or that the clean air hose has been disconnected. These early detections allow the operator to correct the problems when they occur, thus reducing engine wear.
In the preferred embodiment, the air induction system includes an air intake housing with an inlet and an outlet and defining an airflow passageway between the inlet and the outlet. An air filter is mounted within the housing to filter particulates from air flowing through the airflow passageway. A particulate sensor is mounted within the housing downstream from the filter to generate a particulate signal representative of particulate concentration entering the vehicle engine via the outlet.
Preferably, the particulate sensor is a triboelectric sensor that is mounted to an intake manifold or integrated within a mass air flow sensor mounted downstream from the filter for generating a mass airflow signal representative of the amount of air flowing through the passageway. The mass air flow signal can be used for calibration purposes because the output sensor current for a triboelectric sensor is proportional to the square of the velocity of the dust or dirt particulates. This means that the particulate sensor is more sensitive at high flow rates and least sensitive at low flow rates so that a particulate sensing calibration curve can reflect this phenomena.
In one embodiment, air intake housing includes a first airflow passageway for directing airflow from the inlet through the filter to the outlet and a second airflow passageway for directing airflow from the inlet around the filter to the outlet. The second airflow passageway is activated only when the particulate signal is below a predetermined concentration level. In this configuration, an upstream particulate sensor, i.e. a sensor in front of the air filter, is needed. A by-pass mechanism is mounted within the housing upstream from the filter to close off the first airflow passageway and open the second airflow passageway when the particulate signal is below a predetermined concentration level.
The method for monitoring particulate concentration in an air induction system includes the following steps. Air is drawn into the inlet and through the air filter, particulate concentration is sensed downstream from the air filter, and a particulate signal is generated that represents particulate concentration. The signal is sent to an output device. Additional steps include installing a by-pass mechanism upstream from the air filter and activating the by-pass mechanism when the particulate signal is below a predetermined concentration level to direct airflow from the first passageway to the second passageway around the filter.
The subject apparatus provides a simple method for monitoring dust and dirt particulate concentration levels that are entering a vehicle engine. This results in reduced engine wear and can extend filter life when the by-pass mechanism is utilized.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.